The present invention pertains to equipment used in processing photosensitive material, and more particularly to an autoloader for feeding cassettes and/or pallets containing cassettes to and receiving them from a computed radiographic reader.
It is convenient to handle storage phosphorous film/plates within cassettes that protect the film from extraneous light and damage. Storage phosphorous film is read by photoelectrically detecting an image formed by scanning with stimulating radiation. An example of such a scanner/reader is disclosed in U.S. application No. 4,789,782 to O'Hara. It is desirable to retain the x-ray film within a cassette except during actual processing. Such a cassette is disclosed in U.S. patent application Ser. No. 800,799, filed Nov. 27, 1991, entitled "X-ray Cassette Having Removable Photographic Element" by Jeffrey C. Robertson, which is incorporated herein by reference. A hook extractor can be used with the x-ray cassette to move a photographic element to and from an x-ray reader for processing. It is desirable to provide an apparatus to automate the presentation of such x-ray cassettes or similar cassettes to such an extractor so that a number of x-ray cassettes could be processed in succession without attention from an operator. It is also desirable that such an apparatus be able to accurately position x-ray cassettes and/or pallets containing cassettes sequentially to simplify removal and reinsertion of the photographic elements and that the presentation apparatus be separate from the x-ray reader to permit interchange of units and reduce repair time. An example of a suitable device for presenting cassettes is disclosed in copending application U.S. Ser. No. 902,214 filed Jun. 22, 1992, entitled "X-ray Cassette Positioner" of John C. Boutet et al which is also hereby incorporated by reference. In this reference there is disclosed a positioner/autoloader for use with a plurality of x-ray cassettes and/or pallets containing cassettes which comprise first and second cog belts spaced apart so as to provide a plurality of cassette retaining sites one of which defines a cassette read site for presenting of the cassette to the reader. The belts are driven such that the cassettes are each individually positioned at the load site for removal of the photosensitive film therein for reading by the reader after which it is returned to the cassette. The positioner allows a plurality of individual cassettes to be placed thereon for automatic supplying to the reader thus freeing the operator to accomplish other duties. With such positioners it is important to provide a mechanism for properly locating a cassette with respect to the reader so that the reader can unlock the cassette and withdraw the photographic element therefrom. Likewise, the mechanism must be able to remove the cassette from the reader and return it to the cog belt and its appropriate storage position. It is important that the mechanism be designed to operate in such a manner so as to minimize any transfer of vibrations from the autoloader to the reader which can adversely affect the reader reading the information stored on the photo stimulable phosphorous film. It is also important that the cassette be properly positioned each time so that the mechanism for opening the cassette and removing the photo stimulable film is properly oriented so that misalignment of the unlatching mechanism does not occur.
In accordance with the present invention there is provided a mechanism for transferring of cassettes from the autoloader to the reader and back to the autoloader in a reliable manner while also precisely positioning of the cassette within the reader to allow proper clamping of the cassette and permit removal of the storage phosphorous film therein. The mechanism is also designed to minimize transfer of vibration to the reader which can adversely affect the reading of the photographic element.